Another thing to consider is that these are referring to separate worlds. 顕界, genkai refers to this world of the living, and 幽界, yuukai refers to the next world, the world of the dead. I have not seen the original, but I guess neither Stevens nor the AikiNews translators felt that these were idiomatic translations for the context of Ueshiba's speech.

Josh Reyer

The lyf so short, the crafte so longe to lerne,
Th'assay so harde, so sharpe the conquerynge...
- Chaucer